Fraud-detecting telephone toll system.



V. D. CDUSINS. FRAUD DETECTING TELEPHONE TOLL SYSTEM.

APPLICATLON FILED MAILZ, 1916.

Patented Apr. 10,1917.

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ai einm VOLNEY D. COUSNS, GF OAKLAND, CALIFORNIA, ASSIGNOR TO .AMERICAN TELEPHONE AND TELEGRAPI-L COMPANY, OF BQSTON, MASSACHUSETTS, A CORPORATION OF NEW YORK.

Specification of Letters atent.

Patented Apr. l0, i917.,

Application led March 2, 1916. Serial No. 81,710.

To aZZ whom t may concern.'

Be it known that I, VoLNnY D. Cousins, residing at 44.0 Thirty-eighth street, Oakland, in the county of Alameda and State of California, have invented certain Iniprovements in Fraud-Detecting Telephone Toll Systems, of which the following is a specification.

This invention concerns telephone systems in which the prepayment or registration of a toll is necessary to obtain the desired connection. rlhis is customarily eftected by the deposit of a coin of the proper denomination in a boX at the calling substation, thus grounding the lineJ through the resistance of the coin box magnet and operating the line relay to light the line lamp. The users of the telephone sometimes seek to evade payment by connecting a ground to the line independently of the coin boX. By my invention vmeans are provided for both detecting this fraud and preventing connnunication between the calling party and the operator until the call has been regularly initiated. By this improved system positive signals are given the operator of the tact that a subscriber has legitimately .made a call and of the abandonment of efforts to otherwise obtain a connection.

ln the accompanying drawing isshown diagrammatically one arrangement for carrying out the invention.

rit fr appears a telephone substation, this including in addition to the usual equipment a toll apparatus C, which in the present instance consists of a coin box of the well-known type having a collect and refund magnet M and contacts by which one side of the line may be grounded by the colieration of' the approved coin or token. The substation A. is united by line conductors L and L to a jack j at a central station l), there being here connected to the line the line relay r and lamp 0 and the cut-cifrelay 11'. At D are provided a suitable number of special cord or connecting circuits adapted in accordance with my invention for use in switching lines over which the receipt of 'fraudulent callsds anticipated. @ne of these cord circuits c is illustrated. From its plug j? for cooperation with the j ack y', the tip and ring conductors Z and Z of the cord' may be extended through the iront contacts of a 75 ohm marginal relay R and windings ot the repeating coil l to 24 volt central station battery B0. As this invention directly involves only the answering end of the cord circuit, a portion of the calling end is omitted, and of the other usual cord elements attention will merely be called to the answering supervisory relay R0 and the operators listening key K,

which are associated with the circuit in the well-known manner, though the key K has an extra contact 10.

By way of the back contacts of relay R, the tip conductor Z and ring conductor Z are joined to the positive and negative poles of a 32 volt battery B, passing respectively through the 4:20' ohm winding of a polarized relay B and one 200 ohm winding of a differential relay R2 and through the 233 ohm winding of a relay B3 and the other 200 ohm winding of the differential relay. The positive terminal of the battery B is grounded through a 16 volt battery B. Relays R and R2 at their front contacts close a circuit ior a relay R4 from a 24 volt grounded battery B2 to the negative terminal of the batteries B and B in series. At the back contact of relay R a short circuit is completed for the ring conductor winding of the diiferential relay R2. Relay R4 controls at its back contact the 40 ohm shunt 8 of the answering supervisory lamp O, this shunt being independently under the control of the front contact of the answering supervisory relay R0. In addition to its usual `l'unction7 the lamp O is thus caused to serve as a detecting signal. The winding of relay R receives current through the front contacts of relays R and RZ, the special contact 10 of listening key K and a 200 ohm resistance s in parallel with the windingof relay B4'. Included in the sleeve conductor Z2 of the cord circuit c in series with the supervisory lamp O is the 80 ohm winding of a relay B5. This relay, energized from 2e volt battery B3 through the winding ot' 'the cut-oil' relay r o'l the calling line when the operator places the plug 79 in jack j, governs at itsfront contact a locking circuit for relay R and the shunt of the supervisory lamp O which also passes through the front contact of relay R3 and the back Contact of relay B4.

The ground used in the irregular operation of the line signal is naturally of low resistance, and to enable detecting relays B and R2 controlling the supervisory lamp O through the agency ot relay R4 to discrimi nate between this and the normal ground through resistance of the coin box magnet M, the circuit is so arranged that the polarized relay R is energized only when the resistance of the ground at the substationV exceeds approximately 116 ohms and the receiver is removed from its hook. Under such conditions current flows from central to the substation over the conductor L of the line in the direction for which the relay R is polarized to respond. Moreover, the differential relay is so organized that it operates only when the currents in the two windings are unequal, due to a resistance to ground at the substation of less than about 5000 ohms.

It will rst be assumed that the subscriber at A makes a call in the prescribed manner-by taking down the receiver and closing the toll device 10 by supplying the approved coin to the box C, and that pursuant to the illumination of the line lamp the operator at the central station D responds by inserting the plug p of the special cord circuit c in the jack j. A path for current from battery B3 is now completed through the answering supervisory lamp O, winding of relay R5, the sleeve strand Z2 of the cord-and sleeve contacts of the plug p and jack j and the winding ot the cutoff relay r of the calling line. The lamp O lights and relays R5 and r are energized, the latter performing its customary function.

A and B in series through contact of the coin box, winding of magnet M, the hook Vcontact 11 of relay R, conductor 8, winding of relay R3 and the back contact 12 of relay Y R which places a short circuit upon the winding 13 of relay R2. There is also a ,resultant current due to the batteries B and B in opposition, which leaving the central station traverses the winding 14 of relay R2, the winding of polarized relay R, conductor 9, back contact 15 of relay R, the tip strand Z of the cord, the tip contacts of the plug and jack, conductor L, and back through the substation circuit and L side of the line, as previously traced. To this current relays R and R3 respond. `The ditferential relay R2 also attracts its armature and although the opening of contact 12 removes the short circuit and permits current .to flow in its winding 13, the diiierence be- Y tween the current strengths in its two windto Y ings due to the resistance to ground at the substationv is such that the relay remains relay 'R1 through conductor 16, front conf tact 1730i:` relay R2, front contact 19 of Current also Hows from batteries By rela;7 R and conductor 20. At its back contact 18 relay R4 opens the 40 ohm shunt of lamp O which would otherwise exist through resistance s, conductor 21, Contact 18, conductor 22, front contact 23 of relay R3, back contact 24 of relay R and front contact 25 of relay R5. The lamp therefore remains illuminated, contrary to the standard practice, and furnishes the operator a positive indication that the call has been made in a legitimate manner. The operator then throws the listening key K, connecting her set to the talking strands of the cord and closing contact 10. This results in the energization of relay R by way of conductor 26, resistance s, Contact 10, conductors 27 and 16, front contacts 17 and 19 of relays R2 and R, respectively, and conductor 20 to batteries B and B in series, and also to battery B2 through a path in parallel from the point 28 and including the winding of relay R4. Relay R operates, and at its front contact 29 locks itself through the contact 25 of relay R5. At its back contacts 11- and 15 it disconnects the conductors 8 and 9 from the cord strands Z and Z and thus cuts oft the detecting relays R and R2 from the talking circuit. At the front contacts 30 and 31 the talking strands of the cord are connected through to the repeating coil I and battery B0, and the operator may receive the subscribers order. The answering supervisory relay Ro completes the shunt of the lamp O at its front Contact and said lamp is thereby extinguished. The conduct of the remainder of the call presents nothing worthy of note in the present connection.

Considering now the unauthorized or fraudulent calling conditions, any method of procedure other than both removing the receiver from its hook and grounding the line through a resistance of a value between the limits previously specified will fail to energize either relay R or R2, thus leaving a gap in the circuit of relay R4 governing the shunt previously traced for the supervisory lamp O. R4 consequently remains unenergized with its back contact 18 closed, It the subscriber merely takes down the receiver without supplying a coin to the box C, after the operator has plugged into the 'jack 7' with the plug p there is a circuit from battery B through winding 14 of relay R2, winding of relay R', conductor 9, conta'ct 15 of relay R, cord strand Z, tip. contacts of the plug and jack, conductor L of the line, the substation circuit, conductor L, ring contacts of the jack and plug, cord strand Z, contact 11 of relay R, conductor 8, winding of relay R3 and back contact 12 of relay R. The last named relay is operated by current in this direction and at once breaks the short circuit upon the winding of relay R2. This causes the same current to through its Winding 14 as already explainedv in connection with the normal operation oi' the system. In this case, however, due to the diminished resistance to ground at the substation, the resultant current from batteries B and B 'flows over the conductor L from said groundto the central station. This is the wrong direction to operate the polarized relay. Again relay R4 is not operated and its contact 18 remains closed.

Of the contacts other than 18 which have a part in completing the continuity of the shunt for. the lamp O, back contact 24 is closed because its relay R is not energized until thelistening key K is thrown, while in 'both the above described abnormal conditions the front contacts 23 and '25 of relays R3 and R5, respectively, are also closed. Relay R5 operates whenever the plug of the answering cord is in the iack of the calling line, and, with the line and cord thus joined,

relay R3 is energized when the substation hook switch is closed, this being the onlytime at which the illumination of the line lamp willl cause the operator to answer. Therefore, the shunt of the supervisory lamp is complete and said lamp remains dark, informing the operator of the irregularity of the call. Had the listening key K been thrown lwhen the operator answered the irregular call by plugging into the jack of the calling line, there would be a circuit from Qa'volt battery B2 passing through the winding of relay R4, conductor 27, contact 10 of the key K, conductor 26, resistance s and winding of relay R. To the resulting current relay R does not respond. Relay R4 operates, however, and at Contact 18 sevcrs the shunt of the lamp 0. The lighting of this lamp when the listening key is actuated indicates to the operator that the call has been made improperly. I

Upon the operator observing, either from the non-illumination of the supervisory lamp in the normal position of the listening key -or its illumination in the actuated position,

that the subscriber has not satisfied the toll requirements, she may with the listening key normal hold the calling line by retaining the plug in the jack until the subscriber has returned the receiver to its hook, or 'supplied the required coin to the box C. In the first instance the circuit of relay R3 is opened, at the substation hook switch, and in retracting its armature this relay breaks the shunt of the supervisory lamp at contact 23 so that it lights. It, instead, the contact 10 of the box C is closed by a coin, the energization of the detecting relays R 'cept R and R5.

and R2 operates relay R4, which breaks the front contact 18 and the lamp also lights. Upon the display of this signal, the operator throws the listening key. The withdrawal of the signal shows that the call has been legitimately made, while iffit persists, the operator is made aware that the attempt to call has been abandoned. It should be noted that failing to make the call properly strands through to the operators listening key, is by way of the front contacts of the detecting relays R and R2, and these remain inert when a call is irregularly initiated.

Whatever the character of the call, the various relays whose energization has been described will have been released, either by thehanging up of the receiver at substation A or the return et the key K to normal, eX-

The circuit orp relay R5 is opened when the operator withdraws the plug 72 from .the jack j in response to the illumination oit the lamp O. This severs the locking circuit of relay R, and the retraction of its armatures completes the restoration of the apparatus.

Tt will be understood that the arrangement and voltages ot batteries and resistances of the diiferent elements as liereinbefore stated are for a particular application of my invention only, and that they may be widely varied.

l claim as my invention:

1. ln a telephone toll system, the combination with a central station, a. substation and a line connecting the stations, of a toll device at the substation, a signal at the central station, and means including said signal for detecting attempts to simulate the efi'ect of the toll device.

2. Tn a telephone toll system, the combination with a central station, a substation and a line connecting the stations, of a toll device at the substation, a supervisory signal at the central station, and means including said signal for detecting attempts to simulate the e'l'lect of the toll device.

3. Tn a telephone toll system, the combination with a central station, a substation and a line connecting the stations, ot a toll ,device at the substation, a signal at the central station operable legitimately by the toll device and fraudulently iiulependently of said device, and means whereby the legitimate and -fraudulent operation differently affect the signal.

4. In a telephone toll system, the combination with a central station, a substation and a line connecting the stations, of a toll device at the substation, a signal at the central station operable legitimately' by the toll device and fraudulently independently .hook and by the toll device.

6. In a telephone toll system, the combination with a central station, a substation and a line connecting the stations, of a toll device at the substation, a connecting circuit at the central station for switching the line,

Vso

and a supervisory signal in the connecting circuit controlled by the substation switch hook, said signal also being controlled jointly by the switch hook and toll device in a different manner from its control by the switch hook.

7. In a telephone toll system, the combination with a central station, a substation Vprovided with a toll device adapted to be grounded through dii'erent resistances and a line connecting the stations, of a signal at thecentral station operable by said ground connections, and means whereby such ground connections aiect the signal differently.V

8. In a telephone toll system, the combination with a central station, a substation provided with a toll device adapted to be grounded through diii'erent resistances and a line co-nnecting the stations, of a signal atV the central station operable by said ground connections, and means including an operators key whereby such ground connections aii'ect the signal diierently.

9. In a telephone toll system, the combina.- tion with a central station, a. substation and a line connecting the stations, of a signal at the central station operable by ground connectionsV of different resistances at the substation, and means including a listening key whereby such ground connections affect the signal differently.

10. A telephone line, a toll device connected thereto, a switching circuit for the line, a signal in the switching circuit, and means controlling the display of the signal and including a plurality of relays governed by the toll device.

. 11. A telephone line and its substation, a toll device connected to the line at the'substation, a switching circuitY for the line, a'

signal in the switching circuit, and means controlling the display of the signal and including a relay governed by the toll device line, a signal in the switching circuit, and means controlling the display of the signal and including a relay governed by the toll device and a relay governed by the connection between the line and switching circuit.

13. A telephone line, a toll device connected thereto, a switching circuit for the line, a signal in the switching circuit, and means controlling the display of the signal and including an operators key and a plurality of relays one of which is governed by the toll device.

1li. A telephone central station, a substation and a line connecting the stations, a toll device connected to the line at the substation, a cord circuit for switching the line, a. supervisory lamp in the cord circuit, a shunt for the supervisory lamp, and a relay controlled by the toll device for governing the shunt.

15. A telephone central station, a substation and a line connecting the stations, a toll device connected to the line at the substation, a cord circuit for switching the line,

a supervisory lamp and an operators key in the cord circuit, a shunt for the supervisory lamp extending through contacts-of the key, and a relay controlled by the toll device for governing the shunt.

16. A telephone central station, a substation and a line connecting the stations, a toll device connected to the line at the substation, a cord circuit for switching the line, a supervisory lamp and an operators key in the cord circuit, a shunt for the supervisory lamp extending through contacts of the key when said key is'actuated, and a relay controlled by the toll device for governing the shunt.

17. A telephone line and its substation, a toll device at the substation, a connecting circuit for switching the line, a signal, and means controlled by the toll device for governing the signal and the continuity oi the connecting circuit.

18. A telephone line and its substation, a toll device at the substation, a connecting circuit for switching the line, an operators telephone set, a signal, means including said signal ior detecting attempts to simulate the eilect of the toll device, and means controlled by the detecting means for uniting the operators set to the substation line.

19. A telephone line and its substation, a toll device at the substation, a connecting circuit for switching the line, an operators telephone set, a signal, means including said signal for detecting attempts to simulate the eect of the toll device, and means controlled by the detecting means for uniting the operators set to the substation line and disconnecting the detecting means therefrom.

20. A telephone line and its substation, a toll device at the substation, a connecting ators set to the substation line and disconnectingthe detecting means therefrom, and means depending upon the connection of the line and connecting circuit for locking said uniting means independently of the detecting means. i

21. A telephone toll systenicomprisi11g a telephone line and its substation, a toll device at the substation, a cord circuit which may be united with the line, an operators set associated With the cord circuit, toll detecting relays in the cord circuit, and a relay controlled by said detecting relays and governing the connection ot' the operators telephone to the line.

22. A telephone toll system comprising a telephone line and its substation, a toll device at the substation, a cord circuit which may be united With the line, an operators set associated With the cord circuit, toll detecting relays in the cord circuit, and a relay controlled by said detecting relays and governing the connection of said detecting relays to the line.

23. A telephone toll system comprising a JEL telephone line and its substation, a toll device at the substation, a cord circuit which may be united with the line, an operators set associated with the cord circuit, toll detecting relays in the cord circuit, and a relay controlled by said detecting relays and governing the connection of the operators telephone and the detecting relays to the line.

24. A telephone toll system comprising a telephone line and its substation, a toll device vat the substation, a cord circuit which may be united with the line, an operators set associated with the cord circuit, toll detecting relays in the cord circuit, a relay controlled by said detecting relays and governing the connection of said detecting relays to the line, a relay having its Winding in a strand of the cord circuit, and a locking circuit for the connection governing relay extending through a contact of the cord strand relay.

In testimony whereof, l have signed my name to this specification in the presence of two subscribing Witnesses, this 23 day of February 1916.

voLNEY D. cousins.

Witnesses:

C. W. LINDER, A. J. REED.

Copies of this patent may be obtained for ve cents each, by addressing` the Commissioner of Patents, Washington, D. C. 

